The pursuit of high image quality has been a motivation in improving methods and devices for capturing digital images. The quality of a digital image is typically measured by signal-to-noise ratio (SNR). If a uniform area is being captured, the pixel values within an ideal photo of the uniform area should be identical. However, digital cameras are not ideal. Due to the noise introduced from electrical characteristics of sensors, pixel values in a captured photo may have a Gaussian-like distribution around a central value. The SNR may be used to measure a non-ideality in imaging a uniform area.
Conventional approaches for improving the SNR may comprise improving a manufacturing process of sensors in camera equipment so as to increase the image quality, which is in nature equipment upgrading. Such approach may improve image quality to a certain extent while significantly increasing cost to cameras.